1. Field of the Invention
This invention relates to a wire coating resin composition comprising a polyetherketone and an aromatic polysulfone, which is excellent in mechanical, thermal, and chemical properties.
2. Description of the Prior Art
Polyetherketones are crystalline resins having a high glass transition point and melting point (e.g. 140.degree.-145.degree. C. and 330.degree.-335.degree. C. respectively). They have not only excellent properties such as improved resistances to heat, hydrolysis, solvents, radiation, flame and so on but also an extrusion moldability. Therefore, a good deal of attention has been attracted to the application of the heat resistant insulated wire obtained by extrusion coating of polyetherketone around a conducted material to the parts of the airplanes, ships, automobiles or the like. However, they have such defects that high processing temperature is necessary, the elasticity modulus rapidly lowers at over the glass transition point and the creep is large under high loadings.
It is known from the disclosures of Japanese Patent Application "Kokai" (Laid-Open) Nos. 34,512/83 and 202,256/84 that the above-mentioned defects are improved by blending an aromatic polysulfone to the polyetherketone. For example, the former discloses that the insulated wire obtained by extrusion coating the polyetherketone and the polyethersulfone mixed within the range of the weight ratio from 60/40 to 40/60 is preferable in extrusion molding processability and heat resistance, and if the polyethersulfone content is less than the lower limit, the composition obtained is inferior in extrusion molding processability, or, on the contrary, if the polyethersulfone content exceeds the upper limit, the composition obtained is inferior in heat resistance. The latter discloses a composition comprising 2-98% by weight of polyetherketone and 98-2% by weight of aromatic polysulfone. However, the larger the portion of said aromatic polysulfone in the composition, the lower the resistances to solvents, hot water and so on, which is characteristic properties of said polyetherketone.
The demands to the properties of the wire coating resin composition are getting severer and diverser as to the application to the insulated coated wire having a heat resistance becomes wider. So, it has been eagerly desired for the wire coating resin composition to have the characteristic features of the above composition comprising polyetherketone and aromatic polysulfone and improved resistances to solvents and hot water, etc.
The primary object of this invention is to provide a wire coating resin composition comprising a polyetherketone and an aromatic polysulfone, which is improved in solvent resistance and hot water resistance while having a stable moldability.